Patients diagnosed with pulmonary embolism (blood clot in the lung) or deep vein thrombosis (blood clot in a leg vein) are at risk for these blood clots to reoccur. Anticoagulant (blood-thinning) drugs are normally given immediately after the clot is discovered and are continued for a period of 3 or 6 months during which time the risk for recurrence is highest. Research has shown that when oral anticoagulants are used appropriately during this period, patients are less at risk for a recurrent blood clot and this risk reduction outweighs the potential for bleeding to occur.

In this study, patients who had a blood clot in the lung or in a leg vein and completed 6 months of treatment with daily oral vitamin K antagonists (acenocoumarol or warfarin) or once-weekly injections of SR34006 (a new anticoagulant drug) will receive an additional 6 months of once-weekly SR34006 injections or injections of a solution containing no drug (placebo). This trial will evaluate whether patients treated for an additional 6 months with SR34006 have fewer recurrences of blood clots when compared to patients treated with placebo.

Assignment to either SR34006 or placebo will be purely by chance. Neither the patients nor their doctors will know which treatment is being given.